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KECK AND SPITZER FIND FIRST STARS IN DISTANT GALAXIES

KECK AND SPITZER FIND FIRST STARS IN DISTANT GALAXIES

Credit: University of Exeter/Univ. of Wisconsin-Madison/Spitzer/Caltech/UH-IfA

Hydrogen gas `glows' as it absorbs ultraviolet light from young stars. The line emission tells astronomers how much the Universe has expanded since the light left the galaxy.

KECK AND SPITZER FIND FIRST STARS IN DISTANT GALAXIES

Credit: University of Exeter/Univ. of Wisconsin-Madison/Spitzer/Caltech/UH-IfA

Hubble Space Telescope picture of a very distant galaxy. The redshift 5.78 galaxy is the most red object in the field - circled in the center.

MAUNA KEA, Hawaii (April 2nd, 2005) Astronomers have used the Keck, Spitzer and Hubble telescopes to catch the light coming from the first stars to form in some of the most distant galaxies yet seen. Dr. Andrew Bunker of the University of Exeter announced the results show the formation of the first galaxies may have got underway earlier than previously thought.

The team used Hubble Space Telescope data to identify remote galaxies that were suitable for further study. They then analyzed archived images taken at infrared wavelengths with NASA’s Spitzer Space Telescope. Confirmation of their extreme remoteness was provided by the 10-meter Keck II telescope and the Deep Extragalactic Imager and Multi-Object Spectrometer (DEIMOS) in Hawaii.

“We proved these galaxies are indeed among the most distant known by using the Keck telescopes to take a spectrum,” said Dr. Elizabeth Stanway of the University of Wisconsin at Madison.

The Keck spectra showed that the galaxies have redshifts of about 6, which means they are so far away that light from them has taken about 13 billion years to reach us. Telescopes show them as they were when the Universe was less than a billion years old - eight billion years before the Earth and Sun formed.

“The real puzzle is that these galaxies seem to be already quite old when the Universe was only about 5 percent of its current age,” commented Professor Richard Ellis of Caltech. “This means star formation must have started very early in the history of the Universe - earlier than previously believed.”

The light from these first stars to ignite could have ended the Dark Ages of the Universe when the galaxies first “turned on”. It is also likely to have caused the gas between the galaxies to be blasted by starlight - the “reionisation” which has been detected in the cosmic microwave background by the WMAP satellite.

A paper on these results has been submitted for publication in the Monthly Notices of the Royal Astronomical Society.